Liospira micula

• Shell lenticular, with a very low depressed spire
• Shell edges sharply rounded
• Umbilicus filled by a reflexed callosity of the inner lip
• Transverse striae extremely fine and low
• The aperture irregularly triangular in outline, wider than higher
• Diameter of shell usually from 9 to 12 mm

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Ruedemann (1926):

• The average size of L. micula is given as 9-12 mm, in some of our Lorraine horizons the specimens reach little beyond 5 mm while in others they attain their full size.

Foerste (1924):

• Shell lenticular, with a very low depressed spire; sutures not readily recognizeable; edges sharply rounded; umbilicus filled by a reflexed callosity of the inner lip. Surface of this filling concave, but generally distinctly outlined from the remainder of the lower surface of the shell. The slit-band occupies the periphery, but with at least twice as much visible when viewed from above, than when viewed from below. Transverse striae extremely fine and low.
• Locality and Horizon. Originally described from the Maquoketa member of the Richmond formation in Wisconsin, and found at the same horizon in Illinois, Minnesota, and Iowa. It occurs in the Eden formation of Ohio and Indiana, probably also in the Maysville of these states; in the Trenton of Kentucky; and is known, also, from New Jersey, Indiana, and Tennessee. Specimens (No. 8464) 13 to 14 mm. in diameter, with closed umbilicus, similar to Liospira micula, occur in considerable abundance in the loose blocks cast up by the waves on the southeastern shore of Snake island; they are associated with Ctenodonta albertina Ulrich, and belong to the Waynesville member of the Richmond formation.

Weller (1903)

• Description. – Shell small, discoidal-lenticular, consisting of about four volutions. The umbilicus filled by a perfectly smooth, rather distinctly outlined, concave, reflexed callosity of the inner lip. The sutures very shallow; the spire forming an almost continuous, even slope from the apex to the periphery, the apical angle being from 120 to 127 degrees. The periphery of the outer volution is sharply angular in the casts, but is more rounded when the shell is preserved. The volutions subrhomboidal in cross-section. The aperture irregularly triangular in outline, wider than higher, the inner lip nearly vertical. Diameter of shell usually from 9 to 12 mm.

Ulrich & Scofield (1897):

• A small discoidal shell having the umbilicus filled by a reflexed callosity of the inner lip. This filling is concave externally, perfectly smooth, and generally rather distinctly outlined and distinguished from the finely striated under side of the volutions. There are about four volutions, and within these a minute nucleus, the sutures are very shallow, the spire, excepting an occasional slight convexity of the upper whorls, forming an almost• continuous even slope from the apex to the slightly obtuse periphery. The surface markings consist usually of fine lines of growth only, but nearly all of the best specimens show traces of an exceedingly fine set of revolving lines. On the under surface of the whorls the lines of growth make a broad curve, the inner half being the most curved. The band occupies the periphery though somewhat obliquely, nearly twice as much of it being visible in a view of the upper side than is seen in a basal view. It is to be distinguished only on the best specimens, but we have at least fifty before us showing it very clearly. The inner lip is almost vertical in the Trenton variety of the species and always more nearly so than in the Utica form.
• This species rarely, if ever, exceeds 16 mm. in diameter, the average for most localities being 11 or 12 mm. The Maquoketa shales types are commonly less than 10 mm. in diameter. Aside from the fact that it is considerably smaller there is little to distinguish L. micula from L. progne Billings sp. They are doubtless closely related species.

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